/*
** $Id: lstate.h,v 2.133.1.1 2017/04/19 17:39:34 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/

#ifndef lstate_h
#define lstate_h

#include "lua.h"

#include "lobject.h"
#include "ltm.h"
#include "lzio.h"

/*

** Some notes about garbage-collected objects: All objects in Lua must
** be kept somehow accessible until being freed, so all objects always
** belong to one (and only one) of these lists, using field 'next' of
** the 'CommonHeader' for the link:
**
** 'allgc': all objects not marked for finalization;
** 'finobj': all objects marked for finalization;
** 'tobefnz': all objects ready to be finalized;
** 'fixedgc': all objects that are not to be collected (currently
** only small strings, such as reserved words).
**
** Moreover, there is another set of lists that control gray objects.
** These lists are linked by fields 'gclist'. (All objects that
** can become gray have such a field. The field is not the same
** in all objects, but it always has this name.)  Any gray object
** must belong to one of these lists, and all objects in these lists
** must be gray:
**
** 'gray': regular gray objects, still waiting to be visited.
** 'grayagain': objects that must be revisited at the atomic phase.
**   That includes
**   - black objects got in a write barrier;
**   - all kinds of weak tables during propagation phase;
**   - all threads.
** 'weak': tables with weak values to be cleared;
** 'ephemeron': ephemeron tables with white->white entries;
** 'allweak': tables with weak keys and/or weak values to be cleared.
** The last three lists are used only during the atomic phase.

*/

struct lua_longjmp; /* defined in ldo.c */

/*
** Atomic type (relative to signals) to better ensure that 'lua_sethook'
** is thread safe
*/
#if !defined(l_signalT)
#include <signal.h>
#define l_signalT sig_atomic_t
#endif

/* extra stack space to handle TM calls and some other extras */
#define EXTRA_STACK 5

#define BASIC_STACK_SIZE (2 * LUA_MINSTACK)

/* kinds of Garbage Collection */
#define KGC_NORMAL 0
#define KGC_EMERGENCY 1 /* gc was forced by an allocation failure */

// internal global string table
typedef struct stringtable {
  TString** hash; // array for hash table
  int nuse; /* number of elements */
  int size; // size of 'hash' array
} stringtable;

/*
** Information about a call.
** When a thread yields, 'func' is adjusted to pretend that the
** top function has only the yielded values in its stack; in that
** case, the actual 'func' value is saved in field 'extra'.
** When a function calls another with a continuation, 'extra' keeps
** the function index so that, in case of errors, the continuation
** function can be called with the correct top.
*/
typedef struct CallInfo {
  StkId func; /* function index in the stack */
  StkId top; /* top for this function */
  struct CallInfo *previous, *next; /* dynamic call link */
  union {
    struct { /* only for Lua functions */
      StkId base; /* base for this function */
      const Instruction* savedpc;
    } l;
    struct { /* only for C functions */
      lua_KFunction k; /* continuation in case of yields */
      ptrdiff_t old_errfunc;
      lua_KContext ctx; /* context info. in case of yields */
    } c;
  } u;
  ptrdiff_t extra; // for actual 'func' while yield
  short nresults; /* expected number of results from this function */
  unsigned short callstatus;
} CallInfo;

/*
** Bits in CallInfo status
*/
#define CIST_OAH (1 << 0) /* original value of 'allowhook' */
#define CIST_LUA (1 << 1) /* call is running a Lua function */
#define CIST_HOOKED (1 << 2) /* call is running a debug hook */
#define CIST_FRESH \
  (1 << 3) /* call is running on a fresh invocation \
                  of luaV_execute */
#define CIST_YPCALL (1 << 4) /* call is a yieldable protected call */
#define CIST_TAIL (1 << 5) /* call was tail called */
#define CIST_HOOKYIELD (1 << 6) /* last hook called yielded */
#define CIST_LEQ (1 << 7) /* using __lt for __le */
#define CIST_FIN (1 << 8) /* call is running a finalizer */

#define isLua(ci) ((ci)->callstatus & CIST_LUA)

/* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
#define setoah(st, v) ((st) = ((st) & ~CIST_OAH) | (v))
#define getoah(st) ((st)&CIST_OAH)

/*
** 'global state', shared by all threads of this state
*/
typedef struct global_State {
  lua_Alloc frealloc; /* function to reallocate memory */
  void* ud; /* auxiliary data to 'frealloc' */
  l_mem totalbytes; /* number of bytes currently allocated - GCdebt */
  l_mem GCdebt; /* bytes allocated not yet compensated by the collector */
  lu_mem GCmemtrav; /* memory traversed by the GC */
  lu_mem GCestimate; /* an estimate of the non-garbage memory in use */
  stringtable strt; /* hash table for strings */
  TValue l_registry;
  unsigned int seed; /* randomized seed for hashes */
  lu_byte currentwhite;
  lu_byte gcstate; /* state of garbage collector */
  lu_byte gckind; /* kind of GC running */
  lu_byte gcrunning; /* true if GC is running */
  GCObject* allgc; /* list of all collectable objects */ // GCObject.next, weak reference
  GCObject** sweepgc; /* current position of sweep in list */ // GCObject.next
  GCObject* finobj; /* list of collectable objects with finalizers */ // GCObject.next, weak reference
  GCObject* gray; /* list of gray objects */ // ChildObject.gclist
  GCObject* grayagain; /* list of objects to be traversed atomically */ // Table.gclist
  GCObject* weak; /* list of tables with weak values */ // Table.gclist
  GCObject* ephemeron; /* list of ephemeron tables (weak keys) */ // Table.gclist
  GCObject* allweak; /* list of all-weak tables */ // Table.gclist
  GCObject* tobefnz; /* list of userdata to be GC */ // GCObject.next, strong reference
  GCObject* fixedgc; /* list of objects not to be collected */ // GCObject.next, strong reference
  struct lua_State* twups; /* list of threads with open upvalues */
  unsigned int gcfinnum; /* number of finalizers to call in each GC step */
  int gcpause; /* size of pause between successive GCs */
  int gcstepmul; /* GC 'granularity' */
  lua_CFunction panic; /* to be called in unprotected errors */
  struct lua_State* mainthread;
  const lua_Number* version; /* pointer to version number */
  TString* memerrmsg; /* memory-error message */
  TString* tmname[TM_N]; /* array with tag-method names */
  struct Table* mt[LUA_NUMTAGS]; /* metatables for basic types */
  TString* strcache[STRCACHE_N][STRCACHE_M]; /* cache for strings in API */
} global_State;

/*
** 'per thread' state
*/
struct lua_State {
  CommonHeader;
  unsigned short nci; /* number of items in 'ci' list */
  lu_byte status; // status of current lua thread
  StkId top; /* first free slot in the stack */
  global_State* l_G;
  CallInfo* ci; /* call info for current function */
  const Instruction* oldpc; /* last pc traced */ // calling hook for one line
  StkId stack_last; /* last free slot in the stack */
  StkId stack; /* stack base */
  UpVal* openupval; /* list of open upvalues in this stack */
  GCObject* gclist; // g->gray, g->grayagain
  struct lua_State* twups; /* list of threads with open upvalues */ // g->twups
  struct lua_longjmp* errorJmp; /* current error recover point */
  CallInfo base_ci; /* CallInfo for first level (C calling Lua) */
  volatile lua_Hook hook;
  ptrdiff_t errfunc; /* current error handling function (stack index) */
  int stacksize;
  int basehookcount; // how many instructions to execute the hook function
  int hookcount; // instruction count
  unsigned short nny; /* number of non-yieldable calls in stack */
  unsigned short nCcalls; /* number of nested C calls */
  l_signalT hookmask; // call, return, line
  lu_byte allowhook;
};

#define G(L) (L->l_G)

/*
** Union of all collectable objects (only for conversions)
*/
union GCUnion {
  GCObject gc; /* common header */
  struct TString ts;
  struct Udata u;
  union Closure cl;
  struct Table h;
  struct Proto p;
  struct lua_State th; /* thread */
};

#define cast_u(o) cast(union GCUnion*, (o))

/* macros to convert a GCObject into a specific value */
#define gco2ts(o) check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
#define gco2u(o) check_exp((o)->tt == LUA_TUSERDATA, &((cast_u(o))->u))
#define gco2lcl(o) check_exp((o)->tt == LUA_TLCL, &((cast_u(o))->cl.l))
#define gco2ccl(o) check_exp((o)->tt == LUA_TCCL, &((cast_u(o))->cl.c))
#define gco2cl(o) check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
#define gco2t(o) check_exp((o)->tt == LUA_TTABLE, &((cast_u(o))->h))
#define gco2p(o) check_exp((o)->tt == LUA_TPROTO, &((cast_u(o))->p))
#define gco2th(o) check_exp((o)->tt == LUA_TTHREAD, &((cast_u(o))->th))

/* macro to convert a Lua object into a GCObject */
#define obj2gco(v) check_exp(novariant((v)->tt) < LUA_TDEADKEY, (&(cast_u(v)->gc)))

/* actual number of total bytes allocated */
#define gettotalbytes(g) cast(lu_mem, (g)->totalbytes + (g)->GCdebt)

LUAI_FUNC void luaE_setdebt(global_State* g, l_mem debt);
LUAI_FUNC void luaE_freethread(lua_State* L, lua_State* L1);
LUAI_FUNC CallInfo* luaE_extendCI(lua_State* L);
LUAI_FUNC void luaE_freeCI(lua_State* L);
LUAI_FUNC void luaE_shrinkCI(lua_State* L);

#endif
